A gas turbine engine, typically used as a source of propulsion in aircraft, operates by drawing in ambient air, combusting that air with a fuel, and then forcing the exhaust from the combustion process out of the engine. In many gas turbine engines, a fan rotates to draw air into the engine; however, the fan is not a necessity for all gas turbine engines. A compressor section is disposed axially downstream of the fan and includes a plurality of axially aligned stages. Each of these stages includes a rotor, having a plurality of radially outwardly extending and rotating blades, and a stator, having a plurality of radially inwardly extending and stationary vanes. The rotor of each stage compresses air, while the stator realigns the air for optimal compression by the next stage. The compressed air flows from the compressor section through a diffuser and into the combustor, both of which are axially downstream of the compressor. At the combustor, a portion of the air is used to cool the combustor while the rest is mixed with a fuel and ignited.
An igniter generates an electrical spark in the combustor to ignite the air-fuel mixture. The products of the combustion then travel out of the combustor as exhaust and into a turbine section, which is axially downstream of the combustor. The turbine section, having low and high pressure turbines in dual-spool turbine designs, also has a plurality of axially aligned stages. Similar to the compressor, each of the turbine stages includes a stator, having a plurality of radially inwardly extending stationary vanes, and a rotor, having a plurality of radially outwardly extending and rotating blades. Each rotor of the turbine is forced to rotate as the exhaust impinges upon the blades, while each stator re-aligns the exhaust for optimal impingement upon the rotor of the next turbine stage. The fan, compressor section, and turbine section are connected by concentrically mounted engine shafts running through the center of the engine. Thus, as the turbine rotors are rotated by the exhaust, the fan and corresponding compressor rotors are also rotated to bring in and compress new air. Once started, it can thereby be seen that this process is self-sustaining.
The blades of each of these rotors are typically mounted to a central body or disk. In many rotors, a minidisk or seal is connected to and rotates with the body of the rotor. The minidisk and body of the rotor must be locked together to prevent axial and circumferential movement of the minidisk relative to the body of the rotor. Specifically, the first stage of the turbine aft of the combustor, typically has an air seal mounted to the disk of the rotor. This air seal prevents air from bypassing the combustor, except in specific locations where the air is used to cool the turbine sections.
Typically, a bayonet joint, such as the one described in the U.S. Pat. No. 5,468,210, prevents axial movement, while a separate joint prevents circumferential movement of this air seal, or any such minidisk associated with a rotor in such a manner. While effective, these separate joints increase the weight, part count, maintenance, and cost of the engine. The weight and part count of the engine must be kept at a minimum in aircraft applications for optimum efficiency, while the maintenance and cost of the engine are always more desirable when low, no matter the application.